ungetwc(3)

ungetwc3

Un-get wide character from input stream

Usage

#include <stdio.h>

#include <wchar.h>

wint_t

ungetwc(wint_t wc, FILE *stream);

Library

Standard C Library (libc, -lc)

Overview

The ungetwc() function pushes the wide character wc (converted to an wchar_t) back onto the input stream pointed to by stream. The pushed-backed wide characters will be returned by subsequent reads on the stream (in reverse order). A successful intervening call, using the same stream, to one of the file positioning functions fseek(3), fsetpos(3), or rewind(3) will discard the pushed back wide characters.

One wide character of push-back is guaranteed, but as long as there is sufficient memory, an effectively infinite amount of pushback is allowed.

If a character is successfully pushed-back, the end-of-file indicator for the stream is cleared.

Return values

The ungetwc() function returns the wide character pushed-back after the conversion, or WEOF if the operation fails. If the value of the argument c character equals WEOF, the operation will fail and the stream will remain unchanged.

Releases

56 releases since FreeBSD 5.0-RELEASE; the text changed 34 times.

  1. 5.0–5.2.1
  2. 5.3–6.3
  3. 6.4
  4. 7.0
  5. 7.1
  6. 7.2
  7. 7.3
  8. 7.4
  9. 8.0
  10. 8.1
  11. 8.2
  12. 8.3
  13. 8.4
  14. 9.0
  15. 9.1
  16. 9.2
  17. 9.3
  18. 10.0
  19. 10.1
  20. 10.2
  21. 10.3
  22. 10.4
  23. 11.0
  24. 11.1
  25. 11.2
  26. 11.3
  27. 11.4
  28. 12.0
  29. 12.1
  30. 12.2
  31. 12.3
  32. 12.4
  33. 13.0–13.2
  34. 13.3–14.5
  35. 15.0–16.0

Standards

The ungetwc() function conforms to ISO/IEC 9899:1999 (“ISO C99”).

From base 16.0-CURRENT-20261027-61c70dc16a79 in FreeBSD 16.0-CURRENT (2026-10-27). Parsed by carta from the page's mdoc source.